Abstract
Purpose:
MYP1, located in Xq28, is a locus for syndromic and nonsyndromic high myopia. Recent findings indicate that unique haplotypic variants in OPN1LW are responsible for syndromic high myopia at MYP1. The purpose of this study was to identify whether variants in OPN1LW are also responsible for nonsyndromic high myopia at MYP1.
Methods:
Variants in OPN1LW were initially selected from our data obtained from whole exome sequencing in patients with early-onset high myopia. Sanger sequencing was used to confirm the variants. Long-range PCR was used to determine the haplotype and the first gene of the red-green gene array. Candidate variants were further validated in available family members and controls.
Results:
A novel frameshift mutation (c.617_620dup, p.Phe208Argfs*51) and the known unique LVAVA haplotype in OPN1LW were detected in three families with X-linked nonsyndromic high myopia, including the family previously mapped to MYP1. OPN1LW with these variants was the first gene in the red-green gene array. OPN1LW with the novel frameshift mutation is predicted to produce a transcript that would escape from nonsense- mediated decay. These variants co-segregated with high myopia in the three families, with a maximum LOD score of 3.35. These variants were not present in 247 male controls. Clinical evaluation of the patients with variants demonstrated early-onset non-syndromic high myopia, without optic nerve hypoplasia and dichromacy.
Conclusions:
Our results demonstrate that unique variants in OPN1LW are responsible for nonsyndromic high myopia. To our knowledge, this is the first report relating OPN1LW variants with nonsyndromic high myopia. Frameshift mutation in the red-green gene array has not been reported before. This study provides additional evidence to support the idea that variants in OPN1LW are common causes of high myopia—both syndromic and non-syndromic—that maps to MYP1.